Tire sensor modules or transponders which are arranged, for example, in the interior of a tire are known for the purpose of monitoring tire states, in particular a tire pressure, of tires of a commercial vehicle. Such tire sensor modules are configured to capture, in a fixed position, a tire pressure, mechanical stress states in the tire and a tire temperature, to process them and to transmit them by radio-frequency (RF) radio signal to an electronic control unit (ECU) of a monitoring system via a data message. The control unit receives the data message via a receiving module of the monitoring system and, on the basis of limit values, outputs a warning signal to the driver, for example if a tire pressure below a limit value has been determined at one of the tires. US 2007/0018804 discloses an example of such a tire sensor module. Furthermore, a sensor state can be transmitted from a tire sensor module to the control unit via the data message, for example a sensor defect or the presence of a loose tire sensor module, and can be output to the driver via the warning signal.
If the tires of a two-part commercial vehicle including a towing vehicle and a trailer vehicle, that is, a semi-trailer or trailer, are monitored, the tire sensor modules of the towing vehicle are already stored in advance in the control unit by means of a sensor identifier or a sensor identification, the respective tire sensor module being uniquely assigned to a tire of the towing vehicle. If a trailer vehicle is connected to the towing vehicle for a relatively long period, the tire sensor modules of this trailer vehicle may likewise be stored in the control unit and may be uniquely assigned to the individual tires. However, if the trailer vehicle is frequently changed, the tire sensor modules of the trailer vehicle are incorporated by the monitoring system by means of automatic trailer detection. As a result, if the trailer vehicle is changed, there is no need for manual storage, but the respective tire sensor modules of the tires of the trailer vehicle cannot be assigned to a particular tire in a fixed position.
For automatic trailer detection, the monitoring system in a moving commercial vehicle monitors a monitoring region for data messages from any arbitrary tire sensor modules which are not yet known to the control unit. If a new or unknown tire sensor module is captured, it is determined and checked, over a relatively long period of up to 30 minutes for example, whether or not the unknown tire sensor module belongs to the driver's own trailer vehicle. This is carried out, for example, by checking whether or not the tire sensor module concomitantly moves with the towing vehicle over this period by monitoring whether a particular number of data messages are transmitted by this unknown tire sensor module over this period. Once the trailer detection has been concluded, that is, affiliation of the tire sensor module or else of a plurality of tire sensor modules to the driver's own trailer vehicle is determined, the monitoring system is ready to also process and evaluate the corresponding data messages from the tire sensor module and to output warning signals, for example, on the basis of the captured tire states.
The disadvantage in this case is that the incorporation of all tire sensor modules which are detected in the monitoring region and are assigned to the driver's own trailer vehicle takes a very long time and the driver of the commercial vehicle therefore does not receive any feedback relating to the state of the tires of his trailer or relating to the state of the tire sensor module, for example in the event of a defective sensor, until the trailer detection has been completed. In addition, the vehicle must be moving. As a result, the situation can occur in which, if the trailer vehicle is changed, the journey is continued with a defective tire or a defective sensor, as a result of which critical driving situations may arise.